The intent of this document is to provide recommendation for use of detectors for flammable gases, which includes fixed, portable and transportable equipment types, to provide protection from explosion or fires by minimizing the possibility of an accumulation of flammable gases reaching ignitable levels and initiating mitigative actions based upon defined gas concentration limits. There are three independent applications for use of gas detection equipment within hazardous locations: personnel and property protection, classified area surveillance, and supplemental protection for the use of otherwise unsuitable equipment.